1. Field of the Invention
The present invention relates to a conveyor system for use in automobile assembly lines, particularly, in an engine mounting step for mounting an engine on an automobile body.
2. Description of the Prior Art
Referring to FIG. 9, in a conventional conveyor system of the kind described, an assembled engine E is hung from a hanger H and is conveyed to a slat conveyor 81 by means of an overhead conveyor 80, and is shifted onto a carrier jig 82 provided on the slat conveyor 81. Then, while the engine E is being conveyed by the slat conveyor 81, necessary accessories are attached to the engine E. On the other hand, the body B of an automobile after having been equipped is transferred by means of an overhead conveyor 83. While the overhead conveyor 83 runs in synchronism with the slat conveyor 81, the engine E is lifted by the carrier jig 82 and is mounted on the automobile body B. Subsequently, fittings such as wheels and other associated parts are attached to the automobile body B while the overhead conveyor 83 is moving, thus completing the assembly. The assembled automobile is then shifted to the slat conveyor 84 running in synchronism with the overhead conveyor 83. Then, interior parts and accessories are attached to the thus assembled automobile, and gas and oil are supplied, thus finishing the production of the automobile.
This known automobile assembly system has the following disadvantages (a) to (e).
(a) The conveyors 80,81,83 and 84 have to operate in perfect synchronism. Attaining the required synchronism of operation of these conveyors involves fairly troublesome work.
(b) The line speed is limited by the time required for the mounting of the engine on the automobile body, so that it is difficult to increase the production rate.
(c) The slat conveyor has to have a considerable length because the attaching of the engine E to the automobile body B is conducted while the engine mounting slat conveyor 81 runs in a side-by-side relation to the body transferring overhead conveyor 83. The slat conveyor 81 has an endless form so that it is required to have a multiplicity of shifting jigs 82. In consequence, the installation space is increased undesirably.
(d) Each shifting jig 82 must have a driving connection to a power source, in order that these jigs 82 can be power driven. Consequently, an impractically large number of driving connections are required inconveniently.
(e) During mounting of the engine E on the automobile body B, the operator is forced to walk along the slat conveyor 81 at the same speed as the running of the slat conveyor 81 and the overhead conveyor 83, resulting in an impractically large use of labor.